#3 Minor corrections in tutorial

[Anonymous]

In the tutorial on http://catsfoot.sourceforge.net/tutorial.html there are some minor errors:

pop(push(s), some_value).
pop(push(s, some_value)).

Section "Universality of operators" is not clear. In what way does quantifying over non-conforming operators help forbidding them?

should be already understood
should already be handled